Jul 11 2008
In response to the recent hype surrounding hypermiling, I have been meaning to write this article for a little while. Finally I have been able to get around to it. Even if it is not in need of immediate revision, I intend it to always be an open project, so feel free to email me about it anytime.
So, what is hypermiling?
Hypermiling is a term that has been around for a while, I’m not sure how long, but it is generally though to have either come from or been popularized by Wayne Gerdes of cleanMPG.com. On ecomodder.com, the site that I frequent, a hypermiler is someone who acheives 20% above the combined EPA rating for their car.
How does one hypermile their car?
Well, it’s really not all that difficult. The range of hypermiling techniques are quite wide, from easy to very difficult. I’m hoping to address them all, but with the emphasis on the safest and easiest. I will also concentrate on some general tips to help people save gas. Hypermiling your car isn’t always the best way to reduce consumption!
Why should I do it?
There are many reasons that hypermilers do their thing: fun, challenge, environmentalism, and thrift. Depending on the type you are, you will find yourself gravitating to certain groups of techniques. I myself am an environmentalist, so you will see that showing up, be warned!
I will organize this as best as I can, but it may get a little confusing. Please bear with me and feel free to email if you find something amiss.
Section 1: Drive Less
I put this section first because it is the best way to reduce your gas consumption. If this isn’t an option, skip on down, but I think it’s well worth a look for everyone.
1 – Live closer to work
Living near your job will not only reduce your gas consumption, but will reduce stress, be safer, and give you more free time. If you’re spending 10 hours a week commuting, consider a change.
2 – Carpool
Carpooling will not only reduce consumption, but will reduce vehicle wear and tear, saving you a lot of money overall. Carpooling reduces road congestion, and really isn’t all that bad. Make a friend at work and commute together, it’ll be nice not to have to drive all the time!
3 – Bike
If you live close to work, biking can create entire days when you don’t even turn on your car. Even if you don’t live close to work, chances are that you live close to something you do. For those short trips to the bank, the post office, etc., consider getting on the old bike and getting a workout. You’ll enjoy yourself more and won’t be using any gas! Also, keep in mind that short trips are the hardest on your gas mileage. Eliminating all those below-average, around-town trips will boost your mileage without even touching your car.
4 – Combine short trips
You’ve probably heard this a million times, combining trips will save you gas, simple as that.
Section 2: Change your vehicle
Regardless of how you drive or how much you drive, getting a more economical vehicle will help. Check out the 100 Greenest Cars at Yahoo!
1 – Buy a smaller car
This is usually the cheapest and easiest thing. Think about how much size you really need and how often you actually fill your car to capacity. So what if it’s a little squished in the back when you have to haul extra people? That’s never hurt anyone in the past. Moving to a smaller vehicle will save you money in just the vehicle cost, let alone the fuel savings. Just make sure your smaller car isn’t a sports car!
2 – Buy a hybrid
They’re all the rage right now, and for good reason. Honda and Toyota hybrids can regularly dominate their non-hybrid competition. For a bit more money, you get all the comfort of a bigger car and all the economy of a smaller car. Hybrids are generally some of the best cars on the market for pollution and reliability. Don’t let the skeptics get you down about battery replacements and pollution, these claims are greatly over blown.
3 – Buy a motorcycle
Though a motorcycle would be difficult to use as a sole means of transportation, small motorcycles such as the Kawasaki Ninja 250 can be had for about 2000 dollars and will return fuel economy great than 75 MPG and great performance. If you do go this route, don’t forget your gear and your safety course!
4 – Buy a scooter
Just like number 3, but even better mileage! If you live in the city, this is the perfect solution for a lot of people. Honda currently makes the best scooters out there, and a Honda Metropolitan will return over 100MPG. Just don’t buy a 2-stroke and remember the gear and the safety course!
Section 3: Change your driving habits
This is the most important thing you can do when working with an existing vehicle. There are a ton of strategies, but I will try to simplify them to serve as an introduction.
1 – Get instrumentation
The most important thing you can do is get some instant feedback so that you know what’s going on with you car. If you are driving an OBD2 vehicle (1996 and up), go to www.scanguage.com and pick yourself up a Scanguage II. You can also find them on ebay for a little cheaper, but they are indispensable. For older, fuel injected cars, check out the SuperMID. It is more limited in terms of compatibility, but very worth it if you are compatible.
2 – Slow down!
Air resistance increases exponentially with speed, so slow down! The difference between 55 and 75 is astronomical.
3 – Plan your route
One of the easiest things to do is choose a better route to work. In many cases, you may find that you use less gas but get lower mileage, or go further but use less gas, depending on which route you pick. This is why tip 1 of this section is important. Check out this article for more information.
4 – Stop idling
When you idle, you are getting 0 MPG. Idling the car in the cold does not help warm it up, it actually takes longer. Just drive gently after starting up.
5 – Avoid rapid acceleration and hard braking
These sort of actions waste gas. Instead of braking hard, coast from as distance. Use your brakes as sparingly as possible. Also, be aware the slamming the gas will only dump more fuel on than is necessary. Conservative acceleration will generally return the best fuel economy.
6 – Anticipate changes in traffic
If you know that a light is going to become read or turn green, slow down in advance and give it time to do so rather than gunning the gas up to the stop. In heavy traffic give yourself a bit of space before starting up, try to keep moving slowing rather than alternating between fast speeds and stops. This is one of the best tips for driving, as it will prevent you from making many unnecessary stops.
7 – EOC (Engine Off Coast)
Engine off coasting is the way to go to increase fuel economy to astronomical amounts. This is very difficult and can be unsafe, so be very careful when using it. Also be aware that long EOCs can reduce catalytic converter heat and increase emissions (though the time period or relative emissions increases are unknown.
Before EOCing, you need to be aware of how your car will preform under the circumstances. The basic drill is to put the car in neutral, turn the engine off, and turn the key back to run (to give you the use of the speedometer as well as the ability to turn the wheel). EOCing will cause you to lose both power steering and power brakes. You will have a limited power brake reserve, but this depends on each car.
For your first EOC, find a deserted road with a long open stretch and then key off, turn to run, and begin coasting. While coasting, test your steering and your brakes. If they do not feel comfortable, don’t EOC! You don’t want to risk anyone’s life in this pursuit. If steering is okay and the brakes work well, you are ready to EOC in normal driving. Just remember to be very alert and not to EOC in environments likely to have unexpected occurrences. Stay safe!
8 – Draft
On the highway you will notice that SUVs are basically moving walls, pushing all the air out of the way. If you get in behind one, air drag will be cut astronomically. Now, don’t get too close, try to leave 100 feet, or else the trucker will become angry and neither of you will be safe. Even at 100 feet drafting has benefits.
9 – Pulse and Glide
P&G is an interesting technique, taken from the hybrid drivers, which involves alternating EOC and acceleration. P&G is most effectively done at slower speeds, where air drag is not as much of an issue. To P&G you pick a target speed (say 40) and accelerate past it (to 50) and EOC until your speed drops (to 30), you then start up again and accelerate back to the upper target. Rinse and repeat for awesome mileage. Note: This is best done when no one is around and is very annoying to keep up!
10 – Driving with load
In hilly terrain, it can kill FE to be constantly gunning it up hills. DWL involves picking a fixed throttle and slowing down up hills and gaining speed down. Rather than holding speed, you are holding the pedal. This is a very affective way to deal with hills, though you often will need to bend the rules to not slow down traffic too much.
11 – Reduce engine loads
High fans, loud stereos, A/C, and heat add load to the engine and reduce fuel economy. It is much better to roll down your windows than to turn on A/C in almost any circumstance, so keep this in mind. A/C can reduce fuel economy 5-30%.
12 – Turn of 4WD
If you can, turn it off when it is not necessary, it increases driveline losses.
Section 4: Modify your vehicle
Vehicle modifications are some of the most difficult and hardest to quantify changes you can make. Some of them are great, others might seem like more effort than they are worth, and some will be just too hard to do. Pick and choose.
1 – Swap the engine
This depends greatly on your mechanical ability. If you can do it, pick out an engine, and throw it in. This is akin to getting a new car and can give you huge boosts in mileage. I won’t go in depth, however, because I’ll assume that if you know how to do it you can pick out an engine. Perhaps in a later article I will detail the options for Hondas. (Feel free to bug me if you want it done.)
2 – Swap the transmission
Very similar to the above. An auto to manual, like I did, will realize the biggest change. I picked up about 50% on my mileage with this swap. Figure out the gearing on various transmissions and see what suits your needs. You can also swap gears around from within transmission, but then it just gets more complicated! Check out this link for more.
3 – Increase tire pressure
This is one of the easiest ways to increase mileage. I currently have my 44 max psi tired inflated to 50 psi. This doesn’t mean that you should do it, but it has been done by many people. When overinflating, inflate a bit at a time to test handling and feel before you settle somewhere comfortable. Be prepared for a bit rougher of a ride, but you will see the fuel economy increase!
4 – Warm air intake
The WAI will not work for everyone, but it is worth noting because it is a very good mod for Saturn owners. For whatever reason, Saturns really respond to warm air intakes, so take advantage of it of you can. A WAI is generally constructed by extending the stock intake to suck air from closer to the exhaust manifold (where air is warmer). Once again, experiment before you finalize anything.
5 – Block your grill
The air drag caused by the radiator is rather large, so grab that corrugated plastic and block your grill. Be careful to make your first block easily removable and watch the temperature gauge to make sure you don’t overheat. It’s important to find a balance between cooling and aerodynamics, even a partial block will help.
6 – Rear wheel well covers
These snazzy looking covers will help smooth airflow across the car by closing the rear wheel wells. These are affective, though not mind-blowingly so. A must do for anyone with a lot of highway driving or someone interested in aero mods.
7 – Undertray
Covering the entire bottom of the car with corrugated plastic will reduce air drag caused by the roughest surface on most cars. This mod is difficult mainly because you have to get under the car and work on your back securing everything. If you do this, make sure to leave easy access to oil and anything else you might need to get at normally.
8 – Take off the alternator belt
This is a pretty hardcore thing to do, but pays large dividends. By removing the alternator belt you disable the alternator and remove all electrical load from the engine. This means that you will be running down the battery constantly, so to do this you need to minimize electrical loads and run a battery charger at home to keep the battery topped off. There is also the possibility of running a solar car battery charger, though I haven’t heard of anyone experimenting with this yet. Make sure to only remove the belt in case you need to reattach it at some point to deal with rain or darkness!
9 – Replace your radiator fan
If your fan is belt-driven or otherwise inefficient, pick up a new, electric fan to help reduce engine load. This is an especially good modification for those with belt-driven fans, and can save quite a few horsepower.
10 – Remove power steering
For many smaller cars, powering steering is more of a luxury than a necessity. My CRX does not have it and I’ve always been glad of that fact, it makes me feel more connected to the road to have manual steering. That being said, for cars with power steering there are often ways to disable it or to convert the car to manual steering. Also, electric power steering has become an option in recent years. Power steering is just another one of those little things that will rob you of a few HP here and there.
11 – Boattail
This is further down because it is difficult to do, even if it is good for a lot of improvement. A boattail reduces drag caused by turbulence at the rear of the car, which accounts for a large amount of a car’s aero drag. Check out Basjoos’ car in the gallery for some interesting ideas.
12 – Low rolling resistance tires
Much like increasing the tire pressure, LRR tires reduce rolling resistance by using a harder rubber material. They are more expensive and harder to find, but keep them in mind next time you’re shopping for a car.
Good luck and happy hypermiling! Don’t forget to make suggestions.